Well, here's a suggestion:
Sarnissa revels in the bloodshed (I think she's better off staying outside the barrier)
James runs towards Tessar and PUNISHES him along the way
Randel climbs the wall and shoots at Tessar, hoping for a critical hit from aimed shot
Jennifer mows down the spearmen if she can reach them
Libar takes the ring and goes invisible
The archers mow down the remaining archers and, if they manage to do that, the nearest spearmen
Eledar continues to fail, trying to kill a spearman
Wilinilia shoots an aquamarine at Tessar if James couldn't paralyze him. If he managed to do that or the first attack with paralysis procs, then let him shoot at Tessar with emeralds.